Get the Base certification guide and work through that.
Look at the topics listed in the content covered document they provide. If you're unfamiliar with a specific topic then look it up on here, lexjansen.com or a different resource.
Historically you could buy the course notes for $100 instead of taking the course, so if you're in the US or Canada that may still be an option.
I think SAS offers a package that includes the book, a prep test and code for the full exam at a discount that may be worthwhile.